Leptin up-regulates the lactogenic effect of prolactin in the bovine mammary gland in vitro.
The ability of leptin to up-regulate prolactin action in the mammary gland is well established. We examined the effect of leptin and prolactin on traits associated with lactation. Leptin and prolactin enhanced proliferation (thymidine incorporation) of the mammary gland cells, elevated the cells' proliferation in a dose-responsive manner, and synergized to elevate the expression of amino acid metabolism via a 90% increase in aminopeptidase N expression. Leptin and prolactin decreased apoptosis (decreased caspase-3 expression by 60%) in the same manner. Leptin enhanced the effect of prolactin on all of these processes in bovine mammary explants. Leptin and prolactin regulated mTOR (mammalian target of rapamycin) by increasing expression by 66%, which is one of the signal-transduction junctions involved in the regulation of proliferation, apoptosis, and protein synthesis. These findings support the hypothesis that leptin up-regulates prolactin action in the bovine mammary gland.
Feuermann
Y
Y
Institute of Animal Science, Agricultural Research Organization, the Volcani Center, PO Box 6, Bet Dagan 50250, Israel.
Shamay
A
A
Mabjeesh
S J
SJ
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D018826:CD13 Antigens / Q000378:metabolism; D002417:Cattle; D049109:Cell Proliferation / Q000187:drug effects; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D020738:Leptin / Q000494:pharmacology*; D008321:Mammary Glands, Animal / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D011388:Prolactin / Q000494:pharmacology*; D011494:Protein Kinases / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases; D015854:Up-Regulation / Q000187:drug effects
D020738:Leptin; D011388:Prolactin; D011494:Protein Kinases; D058570:TOR Serine-Threonine Kinases; D018826:CD13 Antigens